JP3010822B2 - Manufacturing method of printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board used for various electronic devices such as a personal computer and a word processor.

[0002]

2. Description of the Related Art In recent years, printed wiring boards, which are widely used in various electronic devices, are becoming increasingly compact and lightweight, and have become more and more multifunctional. Conductor patterns and lands formed on insulating substrates are becoming increasingly narrower, thinner, and smaller.

For this reason, solder resists and roadmaps formed on a printed wiring board have been developed for the purpose of preventing solder from adhering to unnecessary portions, protecting the conductive pattern against oxidation, maintaining insulation properties and improving solderability. High resolution, high positional accuracy, and high quality are required, and the forming method is changing from a screen printing method to a photographic developing method using a mask film.

[0004] A conventional method for manufacturing a printed wiring board will be described below. FIG. 2 shows a conventional manufacturing process for forming a solder resist and a road map by a photo-developing method on a printed wiring board. First, in FIG. 2, reference numeral 1 denotes an insulating substrate, 2 denotes a conductive pattern formed on one surface of the insulating substrate 1 with a predetermined wiring pattern, and 3a denotes a photosensitive pattern formed on one entire surface of the insulating substrate 1 so as to cover the conductive pattern. The solder resist ink 3b is a solder resist formed by exposing and developing a predetermined portion of the photosensitive solder resist ink 3a, 4 is a mask film for forming a solder resist, and 5a is a photosensitive resist formed on the solder resist 3b. A road map ink 5b is a road map formed by exposing and developing a predetermined portion of the photosensitive road map ink 5a, and 6 is a road map forming mask film.

[0005] The formation of the solder resist and the road map of the printed wiring board configured as described above will be described below.

First, an etching resist is formed on a copper-clad laminate (not shown) cut to a predetermined size by a screen printing method, a photo-developing method, or the like, and then etched by a solution such as cupric chloride. , To form a conductor pattern 2,
Thereafter, the etching resist is stripped.

After that, as shown in FIG. 2A, a photosensitive solder resist ink 3a is applied to a printed wiring board having a conductive pattern 2 formed on an insulating substrate 1, and touch drying is performed by hot air or the like.

Next, as shown in FIG. 2 (b), the mask film 4 for forming a solder resist is brought into close contact with the surface of the photosensitive solder resist ink 3a which has been dried by touch and exposed to ultraviolet light. Then, the unexposed portion is developed and removed with a predetermined developing solution to form a solder resist 3b.

Thereafter, as shown in FIG. 2 (d), a photosensitive roadmap ink 5a is applied on the solder resist 3b in a slightly wider area than that required for forming the roadmap 5b, and the touch drying is performed in the same manner. . Then, as shown in FIG. 2E, the mask film 6 for forming a road map is brought into close contact with the surface of the road map ink 5a which has been touch-dried, and after being exposed to ultraviolet light, as shown in FIG. The part is developed and removed with a predetermined developing solution.

Then, the solder resist 3b and the road map 5b are processed again with hot air or the like to improve the adhesiveness and hardness of the solder resist 3b and the road map 5b to the insulating substrate and the conductor pattern, and the solder resist 3b and the road map 5b are placed on the printed wiring board. Form.

[0011]

However, in the above-mentioned conventional structure, although the solder resist and the road map have high resolution, there is a risk that undercut occurs even within an appropriate range of touch dry conditions and development conditions. have.

That is, while the cross-sectional shape of the road map formed by the conventional screen printing method is a trapezoid with sharp corners, the cross-sectional shape of the road map formed by the photographic development method is different from the thickness and the exposure of the mask film. It becomes rectangular or inverted trapezoidal due to the light diffraction phenomenon due to the parallelism of the light source and the like. As a result, the road map becomes vulnerable to external force from the lateral direction, and the road map peels off when the printed wiring board is conveyed or when the outer shape is punched by a die, and the yield of the printed wiring board manufacturing process is reduced. It was significantly worse.

Further, even if no peeling occurs during the manufacturing process of the printed wiring board, if an external force or vibration is applied in the manufacturing process of the electronic device or the market, the peeling occurs.
It has problems such as impairing solderability and impairing the function of precision parts.

An object of the present invention is to solve such a conventional problem, and it is an object of the present invention to prevent a road map of a printed wiring board from peeling off.

[0015]

In order to achieve this object, a method for manufacturing a printed wiring board according to the present invention comprises the steps of: forming a conductive pattern on an insulating substrate; and forming the conductive pattern on the insulating substrate so as to cover the conductive pattern. A step of applying and drying a photosensitive solder resist ink, and a mask in which the solder resist pattern and the road map pattern are formed so that the photographic density of the photosensitive solder resist ink increases in the order of a background portion, a road map pattern, and a solder resist pattern. It has a configuration of a step of exposing and developing with a film and a step of forming a road map on a road map pattern portion on the solder resist roughened in the step.

[0016]

A portion for forming a solder resist road map by simultaneously exposing with a mask film on which a solder resist pattern and a road map pattern are formed so that a photographic density increases in the order of a background portion, a road map pattern, and a solder resist pattern. Is roughened.

Thereafter, a road map is formed on the roughened portion of the solder resist surface, whereby the adhesion between the solder resist and the road map can be significantly improved.

[0018]

An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 (a), 1 (b), 1 (c) and 1 (d)
4 shows a process for manufacturing a printed wiring board according to an embodiment of the present invention. In FIG. 1, reference numeral 11 denotes an insulating substrate;
Is a conductive pattern formed on one surface of the insulating substrate 1 with a predetermined wiring pattern, 13a is a photosensitive solder resist ink formed on one entire surface of the insulating substrate 11 so as to cover the conductive pattern 12, and 13b is this photosensitive solder resist. A solder resist formed by exposing and developing a predetermined portion of the ink 13a. Reference numeral 14 denotes a mask film for forming a solder resist having a photographic density difference.
Roadmap pattern 16, Solder resist pattern 1
The road map pattern 16 and the solder resist pattern 17 are formed such that the photographic density increases in the order of 7. Reference numeral 18 denotes a road map which is formed on a roughened portion 19 formed on the surface of the solder resist 13b.

The formation of the solder resist and the road map of the printed wiring board configured as described above will be described.

First, a negative pattern is prepared and prepared as a solder resist and a road map forming mask film used in the manufacture of a normal printed wiring board.
Next, first, a negative pattern of a mask film for forming a solder resist is brought into close contact with an unexposed film having a photosensitive layer applied to a polyester film, and exposed under a normal exposure condition, and then a negative of the mask film for forming a road map is formed. The pattern is brought into close contact with the same position, about 1/3 of the normal exposure
Exposure is performed under conditions of up to 1/5, development is performed under normal conditions, and the background portion 15, road map pattern 1 used in the present invention are exposed.
6. A mask film 14 having a photographic density difference is formed so that the photographic density increases in the solder resist pattern 17 in order.

Next, as shown in FIG. 1A, an alkali-developable photosensitive solder resist ink 13a is applied to the insulating substrate 11 on which the conductor pattern 12 is formed by using a method such as a screen printing method or a curtain coater. Apply, 80 ~
Dry the coating at 85 ° C. for 15-20 minutes.

Next, as shown in FIG. 1 (b), the mask film 14 prepared by the above method is vacuum-contacted on the photosensitive solder resist ink 13a, and is cured by ultraviolet light at an exposure of 400 to 500 mj / m ^2. . Thereafter, as shown in FIG. 1C, a spray pressure of 1.5 wt.
Develop at で 2.0 kg / cm ² for 45-60 seconds. After development, the portion corresponding to the solder resist pattern 17 becomes an unexposed portion and is completely dissolved and removed, and the portion corresponding to the road map pattern 16 has a photographic density lower than that of the solder resist pattern 17, Since the density is higher than that of the other exposed portions, a semi-exposed state is obtained, and the surface is roughened.

Thereafter, an alkali developing type photosensitive road map 18 is applied to the roughened portion 18 of the solder resist 13b by a method such as screen printing and the like, and is dried by touching.
By heating at an atmosphere temperature of 0 to 150 ° C. for 40 to 60 minutes, as shown in FIG.
And a desired printed wiring board on which the road map 18 is formed.

With respect to the printed wiring board according to the present embodiment,
When the adhesion of the road map 18 to the solder resist 13b was examined, it was 6 to 7H in the pencil hardness test, and an improved result with respect to the conventional road maps 3 to 4H could be obtained.

In this embodiment, the printed wiring board is a single-sided printed wiring board, but may be a double-sided or multilayer printed wiring board. Although the photosensitive solder resist ink 13a is of an alkali developing type, it may be of a solvent developing type, and the road map 18 is of a photosensitive alkali developing type, but may be of a UV curable type or a thermosetting type for screen printing. Has the same effect.

[0027]

As described above, according to the present invention, since the road map is formed on the roughened solder resist, the adhesion between the solder resist and the road map is significantly improved, and the peeling of the road map is suppressed. Thus, the yield of the manufacturing process of the printed wiring board can be improved, and the printed wiring board that improves the reliability of the electronic device can be realized.

[Brief description of the drawings]

FIGS. 1A to 1D are cross-sectional views of main steps in a method for manufacturing a printed wiring board according to an embodiment of the present invention.

FIGS. 2A to 2F are cross-sectional views of main steps in a conventional method for manufacturing a printed wiring board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Insulating substrate 12 Conductor pattern 13a Photosensitive solder resist ink 13b Solder resist 14 Mask film 15 Background part 16 Road map pattern 17 Solder resist pattern 18 Road map 19 Roughened part

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-166790 (JP, A) JP-A-3-166789 (JP, A) JP-A-3-161993 (JP, A) JP-A-2- 239689 (JP, A) JP-A-2-158189 (JP, A) JP-A-2-36589 (JP, A) JP-A-61-181189 (JP, A) JP-A-57-36894 (JP, A) Hikaru Hei 2-146470 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H05K 3/00-3/46

Claims (1)

(57) [Claims] 1. A step of forming a conductive pattern on an insulating substrate, a step of applying and drying a photosensitive solder resist ink on the insulating substrate so as to cover the conductive pattern, and a step of applying the photosensitive solder resist ink to a background portion. Exposure and development with a mask film on which a solder resist pattern and a road map pattern are formed so as to increase the photographic density in the order of a solder map, a road map pattern, and a solder resist pattern, and a road map on the solder resist roughened in the process. A method for manufacturing a printed wiring board, comprising a step of forming a road map on a pattern portion.